Traditional door assemblies have a central refractor flanked by separate and discrete diffuser panels. Metal frames extend down the middle of the door assembly along the length of the door assembly. The refractor is typically fastened to these metal frames or snap-fitted over the metal frames to retain the refractor on the door assembly. The frames are visible and appear as dark lines extending down the length of the fixture, thereby detracting from the appearance of the fixture. Another typical door assembly technique substitutes the central metal frame members with translucent plastic frame members. This detracts from the appearance as well, because this technique also creates dark areas that extend down the length of the fixture.